The General Directorate of Civil Protection and Emergencies warns of a drop in temperatures due to the entry into the Peninsula of an arctic air mass that will lead to snowfall at low levels in the northern third. The situation will increase and on Thursday the thermal drop will be even more pronounced being able to place the snow level below 600 meters. This scenario will be maintained until the last hours of Friday.

According to the State Meteorological Agency (AEMET), from tomorrow Wednesday 19 will be established in the Cantabrian a humid flow of northern component with great maritime route, which will give rise to moderate and persistent rainfall, especially during the second half of the day. They will be in the form of snow from about 900- 1200 meters, exceeding thicknesses of 5 centimeters in points of the Cantabrian mountain range and the northern face of the Pyrenees.

With the progressive entry of the Arctic mass, the snow level will fall rapidly during Thursday until it is generally below 600 meters in the northern third of the peninsula, with snowfall that may affect not only mountainous areas, but also surrounding low areas from midday, such as interior points of the Basque Country, Navarre and the north of the Northern Plateau. They will be especially copious in the Cantabrian mountain range, where more than 20 centimeters can be accumulated locally in 24 hours.

The height of the episode is expected between the last hours of Thursday 20 and the morning of Friday 21, when the snow level will be around 300-400 meters in the eastern Cantabrian and upper Ebro, without ruling out that there will be additional collapses locally. The impact may be significant in this area, with accumulations likely to exceed 3-5 centimeters, affecting important communication routes. In addition, during Friday more than 10-20 centimeters could be accumulated again in mountain points of the northern third of the peninsular. Less significantly, the snowfall will also affect the Iberian and Central systems during the episode, without ruling them out in the Catalan pre-Pyrenees.

As for the temperatures, they have already begun to fall today, Tuesday, especially in the northern half, with frosts that have gained extension in mountainous areas. In the following days moderate thermal decreases will be generalized, without ruling out that they are locally notable. In this way, the maximums are expected to be below 10ºC in large areas of the Peninsula, except for the southwest quadrant and the coastlines, where they will be slightly higher. The frosts will gain spatial coverage, being able to be strong in the Pyrenees and moderate in the rest of mountainous environments of the northern half and the Betics. They will be weak in other points of interior, highlighting the North Plateau.

From Saturday afternoon, and in an environment of increasing uncertainty, the most likely scenario indicates that a warmer mass of Atlantic air would penetrate that would begin an ascent of both temperatures and the snow level, and that it would be maintained in subsequent days, thus progressively leaving snowfall and frost restricted to mountain areas.